The present invention relates to a pipe coupling socket for connecting a socket and a plug detachably to each other by operating the operating sleeve, with a locking member equipped in the socket.
A great number of pipe couplings, each of which consists of a socket having a locking member which is pushed in or released by the operating sleeve, and a plug having a stopper groove used for stopping or releasing the locking member, are manufactured and widely used. Conventionally, pipe couplings of the above-described type have a structure in which the operation sleeve proceeds to press the locking member and it moves backwards to release the member. Of the pipe couplings having the above-described structure, there are a number of types having operation sleeve lock means for preventing the operation sleeve from moving backwards undesirably while the socket and plug are in the connection state.
As an example of the conventional pipe coupling having such operation sleeve lock means, the type having a structure in which a separate lock member is fitted together with the operation sleeve around the circumference of the main body of the socket, is known (Japanese Patent No. 2630584).
However, such a pipe coupling having a separated lock member involves a more number of parts by the lock member, and the number of steps for the assembling is increased, thus raising the production cost. Further, in terms of the operation, both of the operation sleeve and the lock member must be operated, and therefore the connection and separating operations for the socket and plug become more laborious than usual.